Vacuum switch

ABSTRACT

A vacuum switch has a pair of disk shaped switching contacts relatively separably located in an evacuated housing with one of the contacts attached to a central electrically conductive supporting member surrounded coaxially by a coil in electrically parallel relation to the supporting member at the switching contact, and the coil is connected to areas of the contact separated from the central portion of the contact by an at least partial separation in the form of a ring-shaped groove or complete annular separation, thus equipping the switch for very high cut-off electrical currents.

United States Patent 11 1 1111 3,852,555

Schuiicker'et al. Dec. 3, 1974 [54] VACUUM SWITCH 3,244,843 4/1966 Ross 200 144 B 3,246,979 41966 L' ff t t l. 200 M4 B [75] Inventors: Dieter Schuocker, W1en, Austria; I er y e a g Joachlm Lippmann Boxdorf Primary ExaminerR0bert S. Macon ermany Attorney, Agent, or Firml-Iill, Gross, Simpson, Van [73] Assignee: Siemens Aktiengesellschaft, Berlin, Santen, Steadman, Chiara & Simpson Munich, Germany 22 Filedi July 17, 1973 [571 ABSTRACT A vacuum switch has a pair of disk shaped switching [21] Appl' 379995 contacts relatively separably located in an evacuated housing with one of the contacts attached to a central [30] Foreign Application Priority Data electrically conductive supporting member sur- Ju|y 19 1972 Germany 2235359 rounded coaxially by a coil in electrically parallel relation to the supporting member at the switching [52 us. (:1 200/144 B, 200/147 R Contact, and the Coil is connected to areas of the [51] Int. Cl. H0lh 33/66 Contact Separated from the central Portion of the 58 Field of Search 200/144 B, 147 R Contact by an at least partial Separation in-the form of a ring-shaped groove or complete annular separation, 5 References Cited thus equipping the switch for very high cut-off electri- UNITED STATES PATENTS currents- 3,196,236 7/l965 Jennings 200/144 B 2 Claims, 3 Drawing igur s 1 VACUUM SWITCH This invention relates to vacuum switches and'is more particularly concerned with such switches wherein a pair of disk-shaped switching contacts are located within an evacuated housing and can be separated from each other, one of the contacts being at tached centrally to an electrically conductive supporting member coaxially surrounded by a coil connected to the switching contact electrically parallel to the central supporting member.

A vacuum switch of. this general type is represented inpublished German application No.l,590,356. However in the switch of that publication the central supporting member is a tubular component havingonly the basic purpose of serving as a mechanical attachment of the associated switching contact; A coil which is in the form of a helical conductive winding arranged in electrically parallel relation thereto has a lower electrical impedance than the tubular component so that current flowing through the vacuum switch travels predominantly through the coil. It is the purpose of this prior arrangement to cause a magnetic dispersion field at the side of the winding facing the switching contact as a result of the current flowing through the helic winding of the magnetic coil field whereby to effect rotation of the cut-off electric are on the contact surface of the-circuit contacts. In this prior vacuum switch the helically' shaped conductive winding is permeated in the closed conditionof the circuit contacts as well as during the entire cut-off process by the largest part of the electrical current. Thus the vacuum switch has a veryhigh self-inductivity which adversely influences its operational behaviorin the closed condition of the circuit contacts. This high inductivity is especially undesirable during the cut-off since thereby a high counter-voltage is induced which leads to-renewed triggering after extinction of the cut-off electric arc. Basically, in a vacuum switch the high current electric arc can be shifted or displaced without a disturbing increase of inductivity from the inner electrode regions to the outside by magnetic means and an annular movement of the are on the electrodes can be achieved by providing the electrodes with a spiral shape so that the current in the electrodes flows tangentially to the circumference of the switching electrode (compare for instance German Pat. No.

1,088,132). The thus required shaping of the elecent.

Another object of the invention is to provide a vacuum switching tube wherein in spite of simple contact geometry and little self-inductivity an even rotation of the cut-off or break-away electric arc on the active electrode surface is assured in order to achieve an even thermic stress of the contact surfaces.

proved construction as will hereinafter become'appar- Another object of the invention is to provide a new and improved vacuum switch embodying a novel relationship of central supporting structure, contact structure and coil structure.

A further object of the invention is to provide new and improved arc suppression and dispersion in a vacuum switch.

Yet another object of the invention is to provide new and improved means in a vacuum switch for radially biasing the cut-off or break-away electric arc.

Yet another object of the invention is to provide improvements in the efficiency and operation of vacuum switches.

Other objects, features and advantages of the invention will be readily apparent from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawing although variations and modifications may be effected without departing from the spirit and scope of the novel concepts embodied in the disclosure, and in which:

FIG. 1 is a longitudinal sectional elevational view through a simplified embodiment of a vacuum switch according to the present invention. Y

I FIG. 2 is an enlarged illustrative sectional elevational view of the two switching'contacts and associated structure of FIG. 1.

FIG. 3 is a sectional plan view taken substantially along the line III-III of FIG. 2.

For illustrative purposes, the vacuum switch as shown'in FIG. 1 is simplified to the most basic parts comprising an evacuated chamber defined within a preferably cylindrical housing 1, of suitable insulating,

'die lectric'material such as glass or ceramic closed at I opposite ends by respective end plate closures 2 and 22 face each other. One of the contacts herein the contact 4 is attached to a relatively large mass supporting rod member 7 which extends fixedly through the closure 2 so that its outer end can-be connected in an electrical circuit. The other contact 5 is centrally supported by a relatively large mass metallic rod-member 6 which extends through the enclosure 22 for connection in an electrical .circuit. To enablemaking and breaking a circuit by closing and separating the switch contacts 4 and 5, the supporting member 6 is reciprocably mounted to 'move axially freely through'the enclosure 22, with a As best seen in FIGS. 1 and 2, the'switching contacts 4 and 5 are generally allochiral in shape, comprising plate disks of substantial mass formed from any suitable electrically conductive material, provided with respective contact surfaces 4a and 5a which are in parallel planes in central contact portions thereof and taper away from the central contact portions in a substantial annular area thereabout. Each of the contacts has inits contact surface a central recess 9, as is customary. Attachment of' the contacts 4 and 5 to their respective supporting members 7 and 6 is in any preferred permacontact geometry and little self-inductivity, to assure uniform rotation of the electrical break-away arc on the active electrode surface, achieving uniform thermic stress of the contact surfaces. To this end, the central supporting member 6 for the contact 5 has a high electrical conductivity in comparison to a coil structure connected to and between the member 6 and the contact 5. Furthermore, the coil 10 is connected to a portion of the contact 5 which is at least partially separated from the central portion of the contact to which the supporting member 6 is attached. Desirably the construction and arrangement are such that the central supporting member 6 serves as a conductor with high conductive value in the closed condition of the vacuum switch so that current .flow will be largely through the central supporting part, while the coil 10 is relatively low in current conducting capacity and thus of low inductance and is yet sufficient for producing a good dispersion field during break-away arcing. The coil 10 is arranged electrically parallel to the central supporting conductor member 6 and is so arranged that it has a higher electrical resistance than-the supportingconductor member 6. Forlthis purpose, the coil 10 discharges at the switching contact 5 into portions which are at least partially separated from the central area of the-switching contact 5 which has the recess 9 Herein such at-least partial separation is effected between the central portion of the contact 5 and an annular radially outer portion by means of an annulargroove 11 which for partial separation is of a depth to extend almost entirely through the contact 5 from its back surface to its forward surface as shown in full outline inFIG. 2, but whichmay comprise a complete interruption as indicated in dash lines extending from the groove walls to the front surface of the contact as illustrated in FIG. 2. If desired, the groove 1 l'maybe-filled with a highly permeable'rnaterial 1 1 inserted therein.

In the illustrated example, the coil 10 comprises four coilsegments 12 which are disposed at 90 intervals about the central supporting member .6, are secured at one of. their ends in v electrically conductive relation fixedlyto the member 6 as best seen. in FIGS. 2 and 3 and secured at their opposite ends in electrically secure relation to the'annular portion of the contact 5 which is separated from the central portion by the separation gap 11. Each of the coil segments 12 hasaportion 12a which extends radially from the conductor. supporting member 6 to anextent to overlie the radially outer annular at least partiallyseparated portionofthe conductor 5 and there joins'an arcuate portion 12b extending concentrically with the axis of the contact 5toward and terminating in adjacent spaced relation to. the juncture bend between the coil segment portions 120 and 12b of the next adjacent coil segment l2 toward which the portion-12b projects from juncture with its radial portion 12a. Best results are obtained where the portions least partially separated portion of the contact 5 near the separation gap 11 is effected by means of generally axially turned and extending terminal portions 12c on the ends of the coils segment portions 12b remote from the radially extending coil portions 12a. The terminal portions 12c are fixedly secured to the contact 5 in sound electrical connection. Because of the at least partial separation 11 current flowing through the coil 10 remains low during electrical contact of the contacts 4 and 5 and until at break-away the break-away arc triggered about the central recesses 9 moves from the central area of the contact surfaces due to the tangential magnetic field of the radial current loop flowing in the switching contact radially toward the outer perimeters of the contacts across the gap 11. At break-away of the contact 5 relative to the contact 4, current flows to a larger extent via the coil 10. However inductance is so small due to the parallel switching of the four coil segments 12 in quarter windings that it does not have a disturbing effect upon movement of the'break-away are past the at least partial separation 11. I When the break-away arc has traveled outwardly past the at least'partial separation 1l, the' increased current flow throughthe coil 10 causes an axial magnetic alternate magnetic flow as indicated in FIG. 2 by the continuous arrows l3. Thisinducesin the contact 4- circular concentric eddy currents as isindicated in FIG. 2 by the interrupted arrow l4. These create radial magnetic fields at the side of the contact 4-which faces the switching contact 5' and these magnetic fields amerts a tangential force-on the break-away electricarc and causes it to rotate. Where at least partial separation 11 is provided with the ring 11' of highly permeable material suchas iron, concentration of the magnetic field in the at least partial separation is effected. Further, eddy currents inducedby the coil 10 partially balance the inductance of the'coil 10, so that all taken together, inductance of the vacuum switch of thepresent invention. is hardly greater than .in a .vacuum switch without the-coil 10. The reason the coil 10 does not re quire, inductance of any consequence is that to1,establish a magnetic field notorily aradialmagnetic dispersion field component but indirectly throug'hthe induction of eddy currents the oppositely locatedswitch! ing contact the entire axial magnetic field of 'the coil is utilized. Since an unw'eakened permeation of; the magnetic field by the coil 10 in the switching contact breakaway gap is achieved by-the annular. at least partial sep-' aration II, the effective are dis'persion field,is amplifled-v, v As will now be apparent, the break-away arc is-biased' from the central portiontoward the outside perimeter of the switch contacts 4 and '5. Since a larger break away current flows through the coil 10 only: after the break-away electric arc has moved outwardly past-the at least partial separation 11, the arc rotation is amplified suddenly so that partial concentrated overheating of the contact surfaces will be avoidediand the vacuum switch safely interrupts high voltage current. Qf further advantage is the fact that the arrangement of the coil can be varied within substantial limits and yet attain satisfactory results. The particular four coil segments displaced in respect to each other by about 90 and running from the central supporting member and secured to the opposite face of the contact 5 from its contact surface is the preferred arrangement.

It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

We claim as our invention:

1. A vacuum switch having an evacuated housing containing a pair of relatively separable disk-shaped switching contacts, one of which contacts has a central portion attached to a central electrically conductive supporting member which is coaxially surrounded by a coil structure electrically parallel to the supporting member, the improvement comprising:

said coil being connected to an area of said one contact which is spaced from said supporting part;

said area being at least partially separated by a gap from said central portion;

and a permeable material in said gap.

2.,A vacuum switch according to claim 1, wherein said permeable material comprises an iron ring.

3. A vacuum switch according to claim 2, wherein said gap comprises a groove whichextends into said one contact at the same side of the contact as the coil is located.

4. A vacuum switch having an evacuated housing containing a-pair of relatively separable disk-shaped switching contacts, one of which contacts has a central portion attached to a central electrically conductive supporting member which is coaxially surrounded by a coil structure electrically parallel to the supporting member, the improvement comprising: said coil being connected to an area of said one contact which is spaced from said supporting part;

said area being at least partially separated from said central portion; and

said coil comprising a plurality of segments each of which is electrically attached at one end to said supporting member and its opposite end to said 5. A vacuum switch according to claim 4, wherein said one; contact comprises a circular disc, and said area and said central portion are at least partially separated by an annular gap. v

6. A vacuum switch according to claim 5, wherein each of said segments has a generally radially extending portion projecting from said supporting member -in spaced relation to said one contact and across said gap and joined to an arcuate coil portion from which a generally axially extending terminal is attached to said area adjacent to said gap.

7. A vacuum switch according to claim 4, wherein said coil comprises four coil segments which are dis-' placed in respect to each other by 90 and extend from the central supporting part in substantially quartercircular shape relative to the backside of the switching contact.

- 8. A vacuum switch according to claim 4, wherein said at least partial separation comprises a gap, and a permeable material in said gap.

9. A vacuum switch according to claim 8, wherein said permeable material comprises an iron ring.

10. A vacuum switch according to claim 9, wherein said gap comprises a groove which extends into said one contact at the same side of the contact as the coil is located.

. 11. A vacuum switch having an evacuated housing containing a pair of relatively separable disk-shaped switching contacts, one of which contacts has a central portion attached to a central electrically conductive supporting member which is coaxially surrounded by a coil structure electrically parallel to the supporting member, the improvement comprising:

said coil being connected to an area of said one contact which is spaced from said supporting part;

said area being at least partially separated from said central portion;

- said coil comprising a plurality of equal segments extending from said supporting member in a generally common plane spaced from said one contact and having generally axially extending terminals connected to said area.

12. A vacuum switch according to claim 11, wherein four equal coil segments are provided each of which has a radially extending portion from said supporting member, and an arcuate portion extending between said radial portion, and said generally axialterminal of the contact segment.

13. A vacuum switch according to claim 11, wherein said at least partial separation comprises a gap, and a permeable material in said gap.

14. A vacuum switch according to claim 13, wherein said permeable material comprises an iron ring.

. 15. A vacuum switch according to claim 14, wherein said gap comprises a groove which extends into said one contact at the same side of the contact as the coil is located.

l6. In a vacuum switch comprising an evacuated housing which contains a pair of disk-shaped switching contacts which canbe separated from each other, one

of which is attached to a central electrically conductive supporting part which is coaxially surrounded'by a coil structure in electrically aparalle l relation to the central supp'ortingpart at the switching contact, the improvementcomprising:

. 'said' central supporting part being electrically attached to a central portion of the switching contact;

' a portion of the contact radially outwardly from the central portion having the coil electrically attached thereto;

said central portion and said radially outer portion being at least partially separated from one another .by a gap; and said coil comprising four coil segments which are displaced in respect to each other by and extend from the central supporting part in substantially quarter-circular shape relative to the backside of the switching contact. '17. A vacuum switch according to claim 16, wherein said coil segments are in generally parallel plane to the switching contact, have radially extending portions attached to the supporting part and extend across the gap with attachment of the coil segments to said radially outer portion adjacent to said gap.

3,852,555 I a 3 18. A vacuum switch according to claim 16', wherein I comprises a ring of thc material.

Said gap has inserted therein a highly permeable t 20. A vacuum switch according to claim 19, wherein rial. vl9. A vacuum switch according to'claim 18, wherein ""S said' gap is annular and said highly permeable material 5 v 

1. A vacuum switch having an evacuated housing containing a pair of relatively separable disk-shaped switching contacts, one of which contacts has a central portion attached to a central electrically conductive supporting member which is coaxially surrounded by a coil structure electrically parallel to the supporting member, the improvement comprising: said coil being connected to an area of said one contact which is spaced from said supporting part; said area being at least partially separated by a gap from said central portion; and a permeable material in said gap.
 2. A vacuum switch according to claim 1, wherein said permeable material comprises an iron ring.
 3. A vacuum switch according to claim 2, wherein said gap comprises a groove which extends into said one contact at the same side of the contact as the coil is located.
 4. A vacuum switch having an evacuated housing containing a pair of relatively separable disk-shaped switching contacts, one of which contacts has a central portion attached to a central electrically conductive supporting member which is coaxially surrounded by a coil structure electrically parallel to the supporting member, the improvement comprising: said coil being connected to an area of said one contact which is spaced from said supporting part; said area being at least partially separated from said central portion; and said coil comprising a plurality of segments each of which is electrically attached at one end to said supporting member and its opposite end to said area.
 5. A vacuum switch according to claim 4, wherein said one contact comprises a circular disc, and said area and said central portion are at least partially separated by an annular gap.
 6. A vacuum switch according to claim 5, wherein each of said segments has a generally radially extending portion projecting from said supporting member in spaced relation to said one contact and across said gap and joined to an arcuate coil portion from which a generally axially extending terminal is attached to said area adjacent to said gap.
 7. A vacuum switch according to claim 4, wherein said coil comprises four coil segments which are displaced in respect to each other by 90* and extend from the central supporting part in substantially quarter-circular shape relative to the backside of the switching contact.
 8. A vacuum switch according to claim 4, wherein said at least partial separation comprises a gap, and a permeable material in said gap.
 9. A vacuum switch according to claim 8, wherein said permeable material comprises an iron ring.
 10. A vacuum switch according to claim 9, wherein said gap comprises a groove which extends into said one contact at the same side of the contact as the coil is located.
 11. A vacuum switch having an evacuated housing containing a pair of relatively separable disk-shaped switching contacts, one of which contacts has a central portion attached to a central electrically conductive supporting member which is coaxially surrounded by a coil structure electrically parallel to the supporting member, the improvement comprising: said coil being connected to an area of said one contact which is spaced from said supporting part; said area being at least partially separated from said central portion; said coil comprising a plurality of equal segments extending from said supporting member in a generally common plane spaced from said one contact and having generally axially extending terminals connected to said area.
 12. A vacuum switch according to claim 11, wherein four equal coil segments are provided each of which has a radially extending portion from said supporting member, and an arcuate portion extending between said radial portion and said generally axial terminal of the contact segment.
 13. A vacuum switch according to claim 11, wherein said at least partial separation comprises a gap, and a permeable material in said gap.
 14. A vacuum switch according to claim 13, wherein said permeable material comprises an iron ring.
 15. A vacuum switch according to claim 14, wherein said gap comprises a groove which exTends into said one contact at the same side of the contact as the coil is located.
 16. In a vacuum switch comprising an evacuated housing which contains a pair of disk-shaped switching contacts which can be separated from each other, one of which is attached to a central electrically conductive supporting part which is coaxially surrounded by a coil structure in electrically aparallel relation to the central supporting part at the switching contact, the improvement comprising: said central supporting part being electrically attached to a central portion of the switching contact; a portion of the contact radially outwardly from the central portion having the coil electrically attached thereto; said central portion and said radially outer portion being at least partially separated from one another by a gap; and said coil comprising four coil segments which are displaced in respect to each other by 90* and extend from the central supporting part in substantially quarter-circular shape relative to the backside of the switching contact.
 17. A vacuum switch according to claim 16, wherein said coil segments are in generally parallel plane to the switching contact, have radially extending portions attached to the supporting part and extend across the gap with attachment of the coil segments to said radially outer portion adjacent to said gap.
 18. A vacuum switch according to claim 16, wherein said gap has inserted therein a highly permeable material.
 19. A vacuum switch according to claim 18, wherein said gap is annular and said highly permeable material comprises a ring of the material.
 20. A vacuum switch according to claim 19, wherein said ring material is iron. 